Improvement of internal soil drainage and yield on heavy clay soils in the Herbert.

Abstract

The Herbert consists of large areas of clay soils being approximately 60% of soils being sugarcane farmed within the region. These soils are usually nutritionally fertile; however yield potential is limited due to waterlogging. Surface drainage has been improved through laser levelling throughout the district, however yield potential is not fully realised due to limitations associated with internal soil drainage. The soils are prone to significant nitrogen losses associated with denitrification and anaerobic conditions which limit crop growth when waterlogging does occur. The project investigated biological, mechanical and cultural practices which may increase the productivity of these soils. The project has clearly shown that yields can be increased on heavy clay soils in the Herbert through the use of mill ash as a soil amendment. The use of mill ash has also clearly shown that the product will enhance germination, crop establishment and increase stalk density leading to increases in cane yield on heavy clay soils in the Herbert. Qureshi et.al (2000) highlighted that there was significant environmental benefits for transporting and applying mill by-products further from the mill site, to manage environmental hazards. This project has highlighted both the economic and environmental benefits of using mill by-products more effectively in a farming system. During the duration of the project SnE Plant Hire constructed a GPS zonal mill mud and ash applicator and has modified its fleet of trucks to allow for zonal application of mill by-products; this has been a very positive step in the handling and distribution of mill by-products in the Herbert.